issue with jerkyness (jittery rendering/movement) every couple of seconds.

Hi all,

I have noticed a problem with the Unity frame rate appearing to jerk every second or two. I have looked around and it seems I am not the only person with similar problems but there doesn’t seem to be a concrete solution and it is becoming a bit of a deal breaker for me.

I have noticed this since upgrading to Unity 3.5 although that is no guarantee that it wasn’t the case in 3.4.2 as I may just not have been working on a game where it was so noticeable!

I am running the latest version of Unity on a system that should have absolutely no speed issues (i7, 6Gb fast ram, NVidia GTX580, SSD, Windows 7 64 Ultimate).

I set up a test project to see if this was project specific and it seems not. I had a cube with simple transform based movement in front of a stationary camera and the jerkiness was definitely apparent every second or two for what looks like a couple of frames (smooth – jerky – smooth – jerky on a regular pattern).

To eliminate my movement code as the cause I replaced the moving cube with a particle effect emitting reasonably slow moving particles with a long life span so they cross the entire screen. Again with just the particle effect and stationary camera in the scene the jerkiness was apparent.

I tried enabling and disabling vsync, changing the camera mode (perspective/orthographic) and enumerating through the various quality settings and nothing seems to make a difference.

To test it further I loaded up angry bots and again every second or so there is a noticeable jerk although it is harder to see when both the character and camera are moving.

I have updated all my drivers and done a clean install of Unity with no success. In addition, this effect seems to be apparent both in the editor and stand-alone build (although slightly better – it looks like a single jerk every second or two instead of 2-3) and happens on both the systems I have access to (the other one is an i5, 8Gb ram, Windows 7 74 Ultimate, NVidia GTX 295).

As this seems to be the case with a moving cube, particle effect and angry bots I am now convinced it is either specific to my two systems (which run literally everything else absolutely fine) or something in Unity.

It is almost like there is some extra internal processing that is happening every second or so and slowing down the engine or it is dropping frames making the rendering appear jerky.

Can anybody shed some light on this because it is driving me nuts!

I have attached a zip containing simple test project with just the particle effect.

If anybody else has this issue or something related please post a comment. It will be good to understand if this is specific to me or if other users have it as well. Any help or ideas are very gratefully received.

EvilNoodle